Fig. 5
From: Trajectories in nitrogen availability during forest secondary succession: illustrated by foliar δ15N
Changes in foliar δ15N with succession by “space-for-time” substitutions. Gray solid circles and black solid circles represent the foliar δ15N at each site and the mean value of foliar δ15N at the same sampling time, respectively. The blue solid, black solid and red dotted lines represent the simple linear regression, quadratic regression and piecewise linear regression lines, respectively. The inflection points in Boreal Alberta, Boreal northern Sweden (SE), Temperate Michigan, Tropical Molienda and Tropical Santa Rosa were at the 52nd, 123rd, 36th, 22nd, and 40th years, respectively. No inflection points were found in other sites. Details of the site information are listed in Additional file 1: Table S1